The Respiratory System

transcript

The Respiratory

System

Respiration Includes Pulmonary ventilation

Air moves in and out of lungs Continuous replacement of gases in alveoli (air sacs)

External respiration Gas exchange between blood and air at alveoli O2 (oxygen) in air diffuses into blood CO2 (carbon dioxide) in blood diffuses into air

Transport of respiratory gases Between the lungs and the cells of the body Performed by the cardiovascular system Blood is the transporting fluid

Internal respiration Gas exchange in capillaries between blood and tissue cells O2 in blood diffuses into tissues CO2 waste in tissues diffuses into blood

Cellular Respiration

Oxygen (O2) is used by the cells O2 needed in conversion of glucose to

cellular energy (ATP) All body cells Carbon dioxide (CO2) is produced as a

waste product The body’s cells die if either the

respiratory or cardiovascular system fails

The Respiratory Organs

Conducting zone Respiratory passages

that carry air to the site of gas exchange

Filters, humidifies and warms air

Respiratory zone Site of gas exchange Composed of

Respiratory bronchioles Alveolar ducts Alveolar sacs

Conducting zone labeled

Provides airway Moistens and warms air Filters air Resonating chamber

for speech Olfactory receptors

External nose

Conducting zone will be covered first

Nasal cavity Air passes through nares (nostrils) Nasal septum divides nasal cavity in midline (to right & left halves)

Perpendicular plate of ethmoid bone, vomer and septal cartilage Connects with pharynx posteriorly through choanae (posterior nasal

apertures*) Floor is formed by palate (roof of the mouth)

Anterior hard palate and posterior soft palate

* palate

Linings of nasal cavity Vestibule* (just above nostrils)

Lined with skin containing sebaceous and sweat glands and nose hairs

Filters large particulars (insects, lint, etc.) The remainder of nasal cavity: 2 types of mucous membrane

Small patch of olfactory mucosa near roof (cribriform plate) Respiratory mucosa: lines most of the cavity

Olfactory mucosa

Respiratory Mucosa

Pseudostratified ciliated columnar epithelium Scattered goblet cells Underlying connective tissue lamina propria

Mucous cells – secrete mucous Serous cells – secrete watery fluid with

digestive enzymes, e.g. lysozyme Together all these produce a quart/day

Dead junk is swallowed

Nasal Conchae

•Inferior to each is a meatus*•Increases turbulence of air•3 scroll-like structures•Reclaims moisture on the way out

(its own bone)

Of ethmoid

Paranasal sinuses Frontal, sphenoid, ethmoid and maxillary bones Open into nasal cavity Lined by same mucosa as nasal cavity and

perform same functions Also lighten the skull Can get infected: sinusitis

The Pharynx (throat) 3 parts: naso-, oro- and laryngopharynx Houses tonsils (they respond to inhaled antigens) Uvula closes off nasopharynx during swallowing so food doesn’t go into

nose Epiglottis posterior to the tongue: keeps food out of airway Oropharynx and laryngopharynx serve as common passageway for

food and air Lined with stratified squamous epithelium for protection

The Larynx (voicebox) Extends from the level of the 4th to the 6th

cervical vertebrae Attaches to hyoid bone superiorly Inferiorly is continuous with trachea (windpipe) Three functions:

1. Produces vocalizations (speech)

2. Provides an open airway (breathing)

3. Switching mechanism to route air and food into proper channels Closed during swallowing Open during breathing

Framework of the larynx 9 cartilages connected by membranes and ligaments Thyroid cartilage with laryngeal prominence (Adam’s apple)

anteriorly Cricoid cartilage inferior to thyroid cartilage: the only

complete ring of cartilage: signet shaped and wide posteriorly

Behind thyroid cartilage and above cricoid: 3 pairs of small cartilages1. Arytenoid: anchor the vocal cords

2. Corniculate

3. Cuneiform

9th cartilage: epiglottis

Epliglottis* (the 9th cartilage)Elastic cartilage covered by mucosaOn a stalk attached to thyroid cartilageAttaches to back of tongueDuring swallowing, larynx is pulled superiorlyEpiglottis tips inferiorly to cover and seal laryngeal inletKeeps food out of lower respiratory tract

Posterior views

Cough reflex: keeps all but air out of airways

Low position of larynx is required for speech (although makes choking easier)

Paired vocal ligaments: elastic fibers, the core of the true vocal cords

Pair of mucosal vocal folds (true vocal cords) over the ligaments: white because avascular

Glottis is the space between the vocal cords Laryngeal muscles control length and size of opening by moving

arytenoid cartilages Sound is produced by the vibration of vocal cords as air is exhaled

Innervation of larynx (makes surgery at neck risky) Recurrent laryngeal nerves of Vagus These branch off the Vagus and make a big downward loop under vessels, then up

to larynx in neck Left loops under aortic arch Right loops under right subclavian artery Damage to one: hoarseness Damage to both: can only whisper

Trachea (the windpipe)

Descends: larynx through neck into mediastinum Divides in thorax into two main (primary) bronchi 16-20 C-shaped rings

of hyaline cartilage

joined by fibroelastic

connective tissue Flexible for bending

but stays open despite

pressure changes

during breathing

Posterior open parts of tracheal cartilage abut esophagus Trachealis muscle can decrease diameter of trachea

Esophagus can expand when food swallowed Food can be forcibly expelled

Wall of trachea has layers common to many tubular organs – filters, warms and moistens incoming air Mucous membrane (pseudostratified epithelium with cilia and lamina

propria with sheet of elastin) Submucosa ( with seromucous glands) Adventitia - connective tissue which contains the tracheal cartilages)

Carina* Ridge on

internal aspect of last tracheal cartilage

Point where trachea branches (when alive and standing is at T7)

Mucosa highly sensitive to irritants: cough reflex

Bronchial tree bifurcation Right main bronchus (more susceptible to

aspiration) Left main bronchus

Each main or primary bronchus runs into hilus of lung posterior to pulmonary vessels

1. Oblique fissure2. Vertebral part3. Hilum of lung4. Cardiac impression5. Diaphragmatic surface

(Wikipedia)

Main=primary bronchi divide into secondary=lobar bronchi, each suppliesone lobe 3 on the right 2 on the left

Lobar bronchi branch into tertiary = segmental bronchi

Continues dividing: about 23 times Tubes smaller than 1 mm called bronchioles Smallest, terminal bronchioles, are less the 0.5 mm

diameter Tissue changes as becomes smaller

Cartilage plates, not rings, then disappears Pseudostratified columnar to simple columnar to simple

cuboidal without mucus or cilia Smooth muscle important: sympathetic relaxation

(“bronchodilation”), parasympathetic constriction (“bronchoconstriction”)

Respiratory Zone End-point of respiratory tree Structures that contain air-exchange chambers are called alveoli Respiratory bronchioles lead into alveolar ducts: walls consist of alveoli Ducts lead into terminal clusters called alveolar sacs – are microscopic chambers There are 3 million alveoli!

Gas Exchange Air filled alveoli account for most of the lung volume Very great area for gas exchange (1500 sq ft) Alveolar wall

Single layer of squamous epithelial cells (type 1 cells) surrounded by basal lamina

0.5um (15 X thinner than tissue paper) External wall covered by cobweb of capillaries

Respiratory membrane: fusion of the basal laminas of Alveolar wall Capillary wall

Alveolar sac

Respiratorybronchiole

Alveolarduct

Alveoli

(air on one side; blood on the other)

Bronchial

“tree” and

associated

Pulmonary

arteries

This “air-blood barrier” (the respiratory membrane) is where gas exchange occurs Oxygen diffuses from air in alveolus (singular

of alveoli) to blood in capillary Carbon dioxide diffuses from the blood in

the capillary into the air inthe alveolus

Surfactant

Type II cuboidal epithelial cells are scattered in alveolar walls

Surfactant is a detergent-like substance which is secreted in fluid coating alveolar surfaces – it decreases tension

Without it the walls would stick together during exhalation

Premature babies – problem breathing is largely because lack surfactant

Microscopic detail of alveoli Alveoli surrounded by fine elastic fibers Alveoli interconnect via alveolar pores Alveolar macrophages – free floating “dust cells” Note type I and type II cells and joint membrane

Lungs and Pleura

Pleural cavity – slit-like potential space filled with pleural fluid

Lungs can slide but separation from pleura is resisted (like film between 2 plates of glass)

Lungs cling to thoracic wall and are forced to expand and recoil as volume of thoracic cavity changes during breathing

Around each lung is a flattened sac of serous membrane called pleura

Parietal pleura – outer layerVisceral pleura – directly on lung

CXR(chest x-ray)

Chest x rays

Normal female Lateral (male)

Pleura also divides thoracic cavity in three 2 pleural, 1 mediastinal

Pathology Pleuritis Pleural effusion

Relationship of organs in thoracic cavity

Paired lungs occupy all thoracic cavity lateral to the mediastinum

Mediastinum contains (mainly): heart, great blood vessels, trachea, main bronchi, esophagus

Each is cone-shaped with anterior, lateral and posterior surfaces contacting ribs

Superior tip is apex, just deep to clavicle Concave inferior surface resting on diaphragm is

the baseapex apex

base base

Hilus or (hilum) Indentation on mediastinal (medial) surface Place where blood vessels, bronchi, lymph vessel, and

nerves enter and exit the lung “Root” of the lung

Above structures attaching lung to mediastinum Main ones: pulmonary artery and veins and main

bronchus

Medial view R lung Medial view of L lung

Right lung: 3 lobes Upper lobe Middle lobe Lower lobe

Left lung: 2 lobes Upper lobe Lower lobe

Oblique fissure

Horizontal fissure

Abbreviations in medicine:e.g.” RLL pneumonia”

Each lobe is served by a lobar (secondary) bronchus

Each lobe is made up of bronchopulmonary segments separated by dense connective tissue Each segment receives air from an individual

segmental (tertiary) bronchus Approximately 10 bronchopulmonary segments in each

lung Limit spread of infection Can be removed more easily because only small

vessels span segments Smallest subdivision seen with the naked eye is

the lobule Hexagonal on surface, size of pencil eraser Served by large bronchiole and its branches Black carbon is visible on connective tissue separating

individual lobules in smokers and city dwellers

Pulmonary arteries bring oxygen-poor blood to the lungs for oxygenation They branch along with the bronchial tree The smallest feed into the pulmonary capillary

network around the alveoli Pulmonary veins carry oxygenated blood from

the alveoli of the lungs to the heart

Stroma – framework of connective tissue holding the air tubes and spaces Many elastic fibers Lungs light, spongy and elastic Elasticity reduces the effort of breathing

Blood supply Lungs get their own blood supply from bronchial

arteries and veins Innervation: pulmonary plexus on lung root

contains sympathetic, parasympathetic and visceral sensory fibers to each lung From there, they lie on bronchial tubes and blood

vessels within the lungs

Bronchopulmonary – means both bronchial tubes and lung alveoli together Bronchopulmonary segment – chunk receiving air

from a segmental (tertiary) bronchus*: tertiary means it’s the third order in size; also, the trachea has divided three times now

“Anatomical dead space” The conducting zone which doesn’t participate in gas

exchange

Primary bronchus:(Left main)

Secondary:(left lower lobar bronchus)

(supplyingleft lowerlobe)

Does this clarify a little?

Understand the concepts; you don’t need to know the names of the tertiary bronchi

Ventilation

Breathing = “pulmonary ventilation” Pulmonary means related to the lungs

Two phases Inspiration (inhalation) – air in Expiration (exhalation) – air out

Mechanical forces cause the movement of air Gases always flow from higher pressure to lower For air to enter the thorax, the pressure of the air in it

has to be lower than atmospheric pressure Making the volume of the thorax larger means the air inside it

is under less pressure(the air has more space for as many gas particles, therefore it is under less pressure)

The diaphragm and intercostal muscles accomplish this

Muscles of Inspiration

During inspiration, the dome shaped diaphragm flattens as it contracts This increases the height of

the thoracic cavity

The external intercostal muscles contract to raise the ribs This increases the

circumference of the thoracic cavity

Together:

Inspiration continued

Intercostals keep the thorax stiff so sides don’t collapse in with change of diaphragm

During deep or forced inspiration, additional muscles are recruited: Scalenes Sternocleidomastoid Pectoralis minor Quadratus lumborum on 12th rib Erector spinae

(some of these “accessory muscles” of ventilation are visible to an observer; it usually tells you that there is respiratory distress – working hard to breathe)

Expiration

Quiet expiration in healthy people is chiefly passive Inspiratory muscles relax Rib cage drops under force of gravity Relaxing diaphragm moves superiorly

(up) Elastic fibers in lung recoil Volumes of thorax and lungs decrease

simultaneously, increasing the pressure Air is forced out

Expiration continued

Forced expiration is active Contraction of abdominal wall muscles

Oblique and transversus predominantly Increases intra-abdominal pressure forcing the

diaphragm superiorly Depressing the rib cage, decreases thoracic

volume Some help from internal intercostals and latissimus

(try this on yourself to feel the different muscles acting)

Pneumothorax (collapsed lung)

Think about the processes involved and then try and imagine the various scenarios

1. Trauma causing the thoracic wall to be pierced so air gets into the pleura

2. Broken rib can do (1); always do a CXR if there’s a broken rib

3. Visceral pleura breaks, letting alveolar air into pleural space

Pneumothorax

Neural Control of Ventilation Reticular formation in medulla

Responsible for basic rate and rhythm Can be modified by higher centers

Limbic system and hypothalamus, e.g. gasp with certain emotions

Cerebral cortex – conscious control Chemoreceptors

Central – in the medulla Peripheral: see next slide

Aortic bodies on the aortic arch Carotid bodies at the fork of the carotid artery: monitor O2 and

CO2 tension in the blood and help regulate respiratory rate and depth

The carotid sinus (dilated area near fork) helps regulate blood pressure and can affect the rate (stimulation during carotid massage can slow an abnormally fast heart rate)

Peripheral chemoreceptors regulating respiration

Aortic bodies* On aorta Send sensory info to medulla

through X (vagus n)

Carotid bodies+ At fork of common carotid

artery Send info mainly through IX

(glossopharyngeal n)

There are many diseases of the respiratory system, including asthma, cystic fibrosis, COPD (chronic obstructive pulmonary disease – with chronic bronchitis and/or emphysema) and epiglottitis

example:

normal emphysema

you might want to think twice about smoking….

general CXR site:

http://www.radiologyinfo.org/en/info.cfm?pg=chestrad&bhcp=1

CXR atlas: http://www.meddean.luc.edu/lumen/

MedEd/medicine/pulmonar/cxr/atlas/cxratlas_f.htm (penumothorax)

Urinary System

The Urinary System

Function

1. Remove nitrogenous wastes2. Maintain electrolyte, acid-base,

and fluid balance of blood3. Homeostatic organ4. Acts as blood filter5. Release hormones: calcitriol &

erythropoietin

Kidneys as Filters

• Diuretic- loose water; coffee, alcohol• Antidiuretic- retain water; ADH• Aldosterone- sodium & water reabsorption,

and K+ excretion• GFR= 180 liters (50 gal) of blood/day• 178-179 liters are reabsorbed back into

blood• Excrete a protein free filtrate

Maintaining Chemical

Homeostasis

The Urinary System

filtration

tubular reabsorption and secretion

General Functioning

of the Kidney

General Functioning

of the Kidney

“refreshed” blood

Nitrogenous Wastes

ammonia

uric acid

Organs of the

Urinary System

Organs of the

Urinary System

kidneys

ureters

urinary bladder

urethra

renal capsule

renal cortex

renal medulla

renal pelvis

renal pyramids

ureter

Kidney AnatomyKidney

Anatomy

Kidney AnatomyKidney

Anatomy

renal artery

renal vein

nephronnephron

filtration

tubular reabsorption and secretion

Nephron Functioning

“refreshed” blood

artery

afferent arteriole

efferent arteriole

glomerulus

peritubular capillaries

Bowman’s capsule

proximal convoluted tubuledistal convoluted tubule

loop of Henle

collecting duct

renal cortex

renal medulla

Each kidney contains over 1 million nephrons and thousands of collecting ducts

Collecting duct

Loop of Henle

DCTGlomerulus

Glomerular Filtration

afferent arteriole

glomerulus

efferent arteriole

Bowman’s capsule

Filters blood; proteins can’t pass through

Radiographic examinations of the urinary system are among the most common contrast media procedures performed in radiology departments. The urinary system consists of two kidneys, two ureters, one urinary bladder, and one urethra

The two kidneys and the ureters are organs that lie in the retroperitoneal space. These two bean-shaped organs lie on either side of the vertebral column in the most posterior part of the abdominal cavity. The right kidney generally is slightly lower or more inferior than the left because of the presence of the liver. Near the upper medial part of each kidney is a suprarenal (adrenal) gland. These important glands of the endocrine system are located in the fatty capsule that surrounds each kidney.

Each kidney is connected to the single urinary bladder by its own ureter. Waste material, in the form of urine, travels from the kidneys to the bladder via these two narrow tubes, termed ureters. The saclike urinary bladder serves as a reservoir that stores urine until it can be eliminated from the body via the urethra.The Latin designation for kidney is ren, and renal is an adjective that is commonly used to refer to the kidney.

Anterior view Posterior view

Kidneys the posteriorly placed kidneys lie on either side of the vertebral column in the upper posterior abdomen. They lie posterior to the lower portion of the liver on the right and posterior to the lower spleen on the left . The lower ribcage thus forms a protective enclosure for the kidneys.

Ureters most of each ureter lies anterior to its respective kidney. The ureters follow the natural curve of the vertebral column. Each ureter initially curves forward, following the lumbar lordotic curvature, and then curves backward on entering the pelvis. After passing into the pelvis, each ureter follows the sacrococcygeal curve before entering the posterolateral aspect of the bladder

The urethra connects the bladder to the exterior. The urethra exits from the body inferior to the symphysis pubis.The entire urinary system is either posterior to or below the peritoneum. The kidneys and ureters are retroperitoneal structures, whereas the bladder and urethra are infraperitoneal structures.

The usual orientation of the kidneys in the supine individual is shown below. The large muscles on either side of the vertebral column cause the longitudinal plane of the kidneys to form a vertical angle of about 20° with the midsagittal plane. These large muscles include the two psoas major muscles. These muscle masses grow larger as they progress inferiorly from the upper lumbar vertebrae. This gradual enlargement produces the 20° angle, wherein the upper pole of each kidney is closer to the midline than its lower pole

These large posterior abdominal muscles also cause the kidneys to rotate backward within the retroperitoneal space. As a result, the medial border of each kidney is more anterior than the lateral border.

Transverse cross-sectional views through the level of L2 illustrate the usual amount of backward rotation of the kidneys.The normal kidney rotation of about 30° is due to the midline location of the vertebral column and the large psoas major muscles on either side. The quadratus lumborum muscles also are shown on each side just posterior to the kidneys. The deep muscles of the back include the group of erector spinae muscles on each side of the spine.

When posterior oblique projections are used during radiographic studies of the urinary system, each kidney in turn is placed parallel to the plane of the image receptor. The body is rotated about 30° in each direction to place one kidney, and then the other, parallel to the IR plane. A 30° LPO positions the right kidney parallel to the IR, and a 30° RPO positions the left kidney parallel.

Most abdominal radiographs are performed on expiration with the patient supine. The combined effect of expiration and a supine position allows the kidneys to lie fairly high in the abdominal cavity. Under these conditions, the kidneys normally lie about halfway between the xiphoid process and the iliac crest. The left kidney normally lies about 1 centimeter more superior than does the right one. The top of the left kidney is usually at the level of the T11-T12 interspace. The bottom of the right kidney most often is level with the upper part of L3

Because the kidneys are only loosely attached within their fatty capsule, they tend to move up and down with movements of the diaphragm and position changes. When one inhales deeply, the kidneys normally drop about 1 inch (2.5 cm) or one lumbar vertebra. When one stands upright, the kidneys normally drop about one lumbar vertebrae, or 5 centimeters (2 inches). If the kidneys drop farther than this, a condition termed nephroptosis is said to exist. With some very thin and older patients in particular, the kidneys may drop dramatically and end up within the pelvis, which may create problems caused by “kinking” or twisting of the ureters.

The primary function of the urinary system is the production of urine and its elimination from the body. During urine production, the kidneys perform the following functions:

1.Remove nitrogenous wastes

2.Regulate water levels in the body

3.Regulate acid-base balance and electrolyte levels of the blood

Nitrogenous waste products such as urea and creatinine are formed during the normal metabolism of proteins. Buildup of these nitrogenous wastes in the blood results in the clinical condition termed uremia and may indicate renal dysfunction.

The macroscopic internal structure of the kidney.The outer covering of the kidney is termed the renal (fibrous) capsule. Directly under the renal capsule surrounding each kidney is the cortex, which forms the peripheral, or outer, portion of the kidney. Under the cortex is the internal structure termed the medulla, which is composed of from 8 to 18 conical masses termed renal pyramids. The cortex periodically dips between the pyramids to form the renal columns, which extend to the renal sinus.

The renal pyramids are primarily a collection of tubules that converge at an opening at the renal papilla (apex) and drain into the minor calyx. Calyces appear as hollowed, flattened tubes. From 4 to 13 minor calyces unite to form two to three major calyces. The major calyces unite to form the renal pelvis, which appears in the shape of a larger flattened funnel. Each expanded renal pelvis narrows to continue as the ureter. Thus urine formed in the microscopic or nephron portion of the kidney finally reaches the ureter by passing through the various collecting tubules, to a minor calyx, to a major calyx, and then to the renal pelvis.The general term renal parenchyma is used to describe the total functional portions of the kidneys, such as those visualized during an early phase of an intravenous urogram procedure.

The structural and functional unit of the kidney is the microscopic nephron. Approximately one million nephrons exist within each kidney.. Small arteries in the kidney cortex form tiny capillary tufts, termed glomeruli (glo-mer′-u-li). Blood initially is filtered through the many glomeruli.

The ureters transport urine from the kidneys to the urinary bladder. Slow peristaltic waves and gravity force urine down the ureters into the bladder. This is an image taken 10 minutes after injection of contrast media into the bloodstream performed as part of an intravenous urogram procedure.

The renal pelvis leaves each kidney at the hilum to become the ureter. The ureters vary in length from 28 to 34 centimeters, with the right one being slightly shorter than the left.

As the ureters pass inferiorly, they lie on the anterior surface of each psoas major muscle. Continuing to follow the curvature of the vertebral column, the ureters eventually enter the posterolateral portion of each side of the urinary bladder.

The ureters vary in diameter from 1 millimeter to almost 1 centimeter. Normally, three constricted points exist along the course of each ureter. If a kidney stone attempts to pass from kidney to bladder, it may have trouble passing through these three regions.

The first point is the ureteropelvic (u-re′-ter-o-pel′-vic) (UP) junction, where the renal pelvis funnels down into the small ureter. This section is best seen on the radiograph in.

The second is near the brim of the pelvis, where the iliac blood vessels cross over the ureters.

The third is where the ureter joins the bladder, termed the ureterovesical junction, or UV junction. Most kidney stones that pass down the ureter tend to hang up at the third site, the UV junction, and once the stone passes this point and moves into the bladder, it generally has little trouble passing from the bladder and through the urethra to the exterior.

The urinary bladder is a musculomembranous sac that serves as a reservoir for urine. The empty bladder is somewhat flattened and assumes the more oval shape only when partially or fully distended.

The triangular portion of the bladder along the inner, posterior surface is termed the trigone . The trigone is the muscular area formed by the entrance of the two ureters from behind and the exit site of the urethra. The trigone is firmly attached to the floor of the pelvis. The mucosa of the trigone is smooth, whereas the remaining aspect of the inner mucosa of the bladder has numerous folds termed rugae. As the bladder fills, the top of the bladder expands upward and forward toward the abdominal cavity.

The bladder functions as a reservoir for urine and, aided by the urethra, expels urine from the body. Normally, some urine is in the bladder at all times, but as the amount reaches 250 ml, the desire to void arises. The act of voiding (urination) is normally under voluntary control, and the desire to void may pass if the bladder cannot be emptied right away. The total capacity of the bladder varies from 350 to 500 ml. As the bladder becomes more and more full, the desire to void becomes more and more urgent. If the internal bladder pressure rises too high, involuntary urination occurs.

Venipuncture is defined as the percutaneous puncture of a vein for withdrawal of blood or injection of a solution such as contrast media for urographic procedures. In the past, venipuncture for urography was performed by physicians and laboratory or nursing personnel. However, in recent years, venipuncture has become part of the scope of practice for the diagnostic imaging professional.

Before contrast media is withdrawn from any vial or bottle, confirmation of the correct contents of the container, route of administration, amount to be administered, and expiration date is imperative.Water-soluble, iodinated contrast media is used for radiographic examinations of the urinary system. This type of contrast medium can be administered by either bolus injection or drip infusion.

A bolus injection is one in which the entire dose of contrast media is injected into the venous system at one time. This method of administration is used typically for maximum contrast enhancement.

Ch 26: Urinary SystemCh 26: Urinary SystemObjectives

Identify and describe the components of the urinary system and their function

Describe the (histological) organization of the nephron

Identify the blood vessels that supply blood to the nephrons

Describe the blood flow through and around the nephron

Functions of Urinary System (Kidneys):

● Regulate fluid balance (fluid volume) of the body

● Excrete organic waste products and conserve nutrients, etc

Stabilize pH

Regulate ion concentrations in the blood

Kidney Kidney LocationLocation

Lateral to vertebral column high on body wall, under floating ribs in retro-peritoneal position

Surface Anatomy

Size of bar of soap Bean shapedHilus – indentation

Three layers Renal fascia – fibrous tunic Adipose capsule – protects kidney Renal capsule – anchors kidney to body wall,

continuous with peritoneum

Sectional Anatomy

Cortex: outer layer, light reddish brow, granular appearance (due to many capillaries)

Medulla: darker striped appearance (due to tubules) Subdivided into distinct renal pyramids, terminating with a papilla. Separated by renal columns from the cortex.

Fig 26-3

Urine collection:

Ducts within each renal

papilla release urine

into minor calyx

major calyx

renal pelvis

ureter

Renal CirculationRenal Circulation

Segmental arteries

Interlobar arteries

Arcuate arteries

Interlobular arteries

Afferent arterioles

Glomerulus

Efferent arterioles

Peritubular capillaries

Segmental veins

Interlobar veins

Arcuate veins

Interlobular veins

Venules

Renal Artery Renal Vein

Fig 26-4

Functional unit: Nephron

Renal corpuscle: Glomerulus Bowman’s capsule

Tubular passageways with associated blood vessels: PCT LOH DCT CD

(>mio/kidney)

Fig 26-8

Fig 26-6

Filtration: Passage across Three Barriers

Capillary endotheliumFenestrated

What gets through?

Basement membrane

Glomerular epithelium (= visceral layer of Bowman’s capsule)slit pores between pedicels of podocyte

Fig 26-8

Two Types of Nephrons

Cortical nephrons (85%) shorter, mostly in cortex of kidney, produce "standard" urine

Juxtamedullary nephrons (15%), "juxta-next-to" the medulla - responsive to ADH, can concentrate urine

Juxtaglomerular Apparatus

Macula densa

+Juxtaglomerular cells

(smooth muscle fibers from afferent arteriole)

= Juxtaglomerular Apparatus

= Endocrine system structure (renin and EPO)

Urine Transport, Storage, and Urine Transport, Storage, and EliminationElimination

Trace drop of urine from kidneys to outside world

Lining of these parts?

Nephroptosis (= floating kidneys)

Nephrolithiasis

Occurs when urine becomes too concentrated and substances crystalize. Symptoms arise when stones begin to move down ureter causing intense pain.

Kidney stones may form in the pelvis or calyces of the kidney or in the ureter.

Anatomy of Urinary Bladder

Retroperitoneal, behind pubis Internal folds - rugae - permit expansion (max. holding

capacity ~ 1L) Trigone - area at base delineated by openings of ureters and

urethra - without muscle Internal urethral sphincter - involuntary sphincter

Histology1. transitional epithelium2. detrusor muscle – smooth muscle

Fig 26.10

Urethra

External urethral sphincters – voluntary at pelvic floor

Female - short – from base of bladder to vestibule

Male1. prostatic urethra – from base of bladder through

prostate gland2. membranous urethra – between prostate gland &

base of penis3. penile (spongy) urethra – traverses penis to orifice

UTIs (esp. E.coli)

Male versus Female

The End

Kidneys may sustain 90% loss of nephrons and still not show apparent symptoms!!!

2-4 % of population only have 1 kidney!

Manneken PisFountainBrussels, 1619

The Respiratory System

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